The present invention relates to a folding and stacking carrier for loaves of bread and the like. The carrier is tray-like in form and has end walls which can be folded down, for space saving, and which can be erected to support another carrier above it so that the carriers are in spaced, stacked relationship.
Bakeries commonly use tray-like carriers to carry and stack groups of bread loaves. In its simplest form, the carrier comprises a rectangular grid having upstanding walls extending along the side edges thereof. The carrier is usually of solid one-piece construction-that is because it must be particularly rugged, due to the rough handling to which it is subjected, and because it must remain rigid and stable when forming part of a loaded stack that is being moved about.
Some years ago I developed a steel carrier (shown in U.S. Pat. No. 2,994,463) having a rectangular grid floor, a rigid rail or wall extending around the perimeter of the floor and connected thereto, and a pair of opposed collapsible end walls which could be rotated from a collapsed horizontal position, internal of the floor perimeter, to an upstanding position atop the adjacent rails. Locking devices were provided at the ends of the walls to lock them to the rails, so that they formed rigid upward extensions thereof.
These units owed part of their success to the fact that the end walls and locking devices were formed of spring steel, so that the needed rigidity, strength and stability could be obtained.
The steel carriers have enjoyed considerable commercial success. However, their manufacturing cost is now becoming relatively high and it has become desirable to embody the desirable feature of the folding walls in a carrier manufactured of rigid plastic, such as polyethylene.
When prototypes were built of plastic, it was found that corner locking elements were a problem, as the plastic was not strong enough or rigid enough to be suitable. The concentration of forces was too much for the materials used. Significant problems were also encountered in devising a unit which had walls of sufficient stability and rigidity.